Indexing mechanism



Dec. 1l, 1945'- H. v. HOFFMAN Erm.

INDEXING MECHANI SM Filed May 22, 1944 4 Sheets-Sheet 1 f A, sr

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Dec. 1l, 1945. H. v, HoFFMAN ETAL INDEXING MECHANISM Filed May 22, 19444 Sheets-Sheet 2 g IIN.l

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Dec. ll, 1945.

H. V. HOFFMAN ETAL INDEXING MECHANI SM Filed May 22, 1944 4 Sheets-Sheet3 .Dec. ll, 1945. H. v. HOFFMAN ETAL 2,390,649

INDEXING MECHANI SM Filed May 22, 1944 4 sheets-sheet 4 L53 v,/56 ,/0 70f I ivi? I Patented Dec. 11, 1945 INDEXING MECHANISM AHomer VeriinHoffman,

Rcnold Kaufman,

Soutmlyhitley, and Von Pierceton, Iiid., assignors to K M & HCorporation, Fort Wayne, Ind., a corporation of Indiana Application May22, 1944, Serial No. 536,732

14 Claims.

Our invention relates to an indexing mechanism, and in particular to afixture in which a nut blank is positioned and held for a precisiontapping operation.

The precision tool industry has long sought a compact, inexpensive, andyet accurate machine which would position and hold standard nut blanksfor the tapping operation. This machine must also be capable ofautomatic operation, and for synchronization with tapping tool. Ourinvention contemplates such a device.

The principal object of our invention is the provision of a novelindexing mechanism erprecision tapping fixture, wherein a standard nutblank is moved to tapping position, secured during the tapping operationand discharged from the device.

Another object of the present invention is to provide a novel precisiontapping xture which is fully automatic in its operation.

Another object of the present invention is to provide a novel precisiontapping fixture which may be used with ease with a large number ofdiiTerent types and makes of tapping tools.

A further object of the present invention is to provide a novelprecision tapping fixture wherein its operations may be synchronizedwith the tapping tool with which it is used.

Still a further object of the present invention is to provide a novelindexing mechanism which is compact and inexpensive, yet accurate inoperation.

Another object of the present invention is to provide a novel precisiontapping xture in which necessary adjustments may be made without thenecessity of disassembling the machine to any great extent.

A further obiect of the present invention is to provide a novelprecision tapping xture wherein the chips of metal are disposed of sothat they will not easily work in betweenmoving parts oi' the fixture.

And stili another obiect is to provide a device which is very simple inconstruction and can be thoroughly cleaned with ease.

Other objects and advantages will become apparent from the followingdescription taken in.

conjunction with the drawings, of which there are four sheets, and inwhich,

Fig. 1 is a perspective view of our improved indexing mechanism;

Fig. 2 is a top plan View of the most important portions of themechanism with a portion of the feeding tray and the power cylinderomitted;

the operation of the CFI Fig. 3 is a front elevational view of thatportion of the device illustrated in Fig. 2;

Fig. 4 is a cross-sectional view on an enlarged scale takensubstantially on the line 4-4 of Fig 2;

Fig. 5 is a cross-sectional view taken on the line` 5-5 of Fig. 6;

Fig. 6 is a rear elevational view of the indexing mechanism with thepower cylinder and feeding tray omitted, and with the rear wallpartially broken away better to illustrate that portion 0f the mechanismwithin the housing;

Fig. 7 is an enlarged sectional view taken through the plunger, showinga nut blank in tapping position, and

Fig. 8 is a plan view of the stepping mechanism and may be considered astaken substantially on the line 8`8 of Fig. 3.

Referring to Fig. 1, it will be seenthat our indexing mechanism I0 ismounted on a bed plate I2 and comprises in general a power cylinder I4,a housing I6, a notched table or plate I8, and a tray 22 from which thenut blanks are fed. The power cylinder I4 may be of any standard typeand may be operated either by hydraulic or air pressure. 'I'he cylinderillustrated? is operated by air pressure and is of the double actingtype; it is provided with adjustable stops to limit its movement ineither direction. A link 24 operating an air valve 26 is provided toconnect the power cylinder I4 to the tapping tool so that the operationof the fixture may be synchronized with that of the tapping tool. Thecylinder I4 is mounted on a block 28 which'is in turn bolted to thefixture bed I2.

The housing I6 is formed by a pair of vertical plates 30. 32 which arebolted to the bed by bolts 34, 36 and by a block 38 bolted to the topedges of the plates 30. 32 by bolts 40, 42. A bearing block 44 is boltedto the outside of the front wall 32 of the housing by bolts 45 and isformed with a vertically disposed bore 46. A vertically disposed shaft48 is rotatably mounted in the bore 46 of the bearing block 44. Theshaft 48 is provided with a circumferential bearing flange 5I) which istte-fi into a suitable circular bearing 52 formed in the top of thehearing block 44 concentric with the bore 46. The notched table I8 issecured to the shaft 48 by bolts 54 which pass through suitable openingsin the table I8 and into tapped holes in the flange 50.

A plate 56 is secured to the top of the bearing block 44 and liesbeneath the notched table I8; the plate 56 is provided with a circularopening 58 to receive the circular bearing flange 5D. 'I'he partlycircular condguratlon of the plate 88 is indicated in Fig. 2, and itwill be noted that it has a slightly larger radius than the table i8,but is cut or! along a chord so as to be ilu'sh with the joint betweenthe housing I8 and the bearing block 44. as shown at 80 in Fig. 4, andit is cut oif along another chord at 82 (see Fis. 2) to provide a spacewhere the tapped nuts may be dropped free of the notched table I8, aswill be more fully disclosed hereinafter.

The housing I8 is provided with a top plate 84 oi case-hardened steelwhich has its upper surface flush with the upper surface of vthe plate88. 'I'he plate 84 lies over the block 88 and has the same generaldimensions as this block. Positioned on top of the plate 84 is guideplate 88. which has an arcuately formed edge 88 faced toward the outeredge or periphery of the table i8. The radius of the arcuately formededge 88 is only slightly greater than the radius of the table I8, andits function will appear presently. A cover plate 10 lies over the plate88 and over that portion of the notched table I8 which is adjacent thearcuate edge 88. The plates 8B, 88, and 10 are secured to the top of thehousing i8 by suitable bolts 12. The plates 88 and 84 are formed withdepressions 18 and 18, respectively, which are concentric with the axisof the shaftd8 so that any chips of metal which may nd their waybeneath'the notched table may be trapped and will not score the undersurface of the table I8.

The thickness of the table I8 is only slightly less than the depth ofthe nut blank which is being machined, and the slot formed by the plates84, 88 and 18 has a height sucient to permit the nut blanks to be passedtherethrough. It will be seen from Figs. 2 and d that the outer edge 18of the plate 88 and the surface 11 of the platev84 bear against theunderside of the table |8 and form a track on which the nut blanks andtapped nuts may be slid by the rotational movement of the table i8. Asthe finished nuts emerge from the slot. they drop of! the track and freeof the table i8 into a-suitable receptacle.

A sleeve 18 is mounted on the lower end of the vertical shaft 48 bymeans of a tapered pin 88 which passes through holes 82 in the sleeve 18and the tapered bore 84 in the shaft 48. The sleeve 18 is so positionedthat its upper end bears lightly against the lower face of the bearingblock 44 when the bearing flange 50 is seated in the circular bearing62; this arrangement prevents the shaft 48 from moving vertically, butdoes not present appreciable friction which would retard the relativelyfree rotation of the shaft 48 and its associated parts. At the lower endof the sleeve there is provided an integral flange 88 to which a ratchetwheel 88 is secured by bolts 80. One edge of the ratchet wheel projectsthrough an opening 8| inthe wall 32 of the housing I8. The function ofthe ratchet wheel 88 in the rotation of table |8 will appear presently.

Two sets of notches are cut in the periphery of the table |8. One ofthese sets is composed of a plurality of U- haped recesses 82 which aresufficiently wide to receive a standard nut blank-for instance, ahexagonal nut blankacross opposed flat faces thereof. The nut blanks areplaced in the recesses 82 by hand from the tray 22, and as the table isrotated in a clockwise direction (Figs. l and 2) the pointed edges ofthe blank contact an upstandlng ange 94 on the tray 22 so that the blankis properly positioned inthe recesses 82: the nut blank is held in thisrelative position by the arcuate edge 88 of the plate 88. 1

The second set of notches is composed of a plurality of shallow V-shapedrecesses 88 which are positioned intermediate the U-shaped recesses 82.there being an equal number of each of the recesses 82.and 88. Asimilarly shaped, but very slightly larger, notch 88 is formed in theperiphery of plate 88 and each of the notches 88 coincides with thisnotch when the notches 82 present a nut blank at the tapping position.'I'he table i8 is prevented from rotation during the tapping operationby a detent |00 which engages in the coinciding notches 88, 88. Thedetent |00 is pivotally mounted on a shaft |02 which is mounted in ablock |04 bolted to a plate |08 by suitable bolts |08. Because thenotches 88 are placed intermediate adjacent notches 82, the detent |00may not be positioned diametrically opposite the tapping position andthe block |04 is formed with non-parallel edges so that it will hold thedetent |00 in the proper position. The plate |08 is mounted to thebearing block 44 -by bolts I I0. So that the detent will have a positiveaction it is urged toward notch-engaging position by a spring ||2 whichis held in a bore lli in the block |08 and is engaged at its free end bya pin |18 mounted in the lower end o! the detent |00.

As the table is rotated under the influence of the stepping mechanism20, the detent |00 is disengaged from the notch 88 by the force of themovement and is prevented from entering into the recesses 82 by thenotch V88. The wide V- shape of the notches 88 facilitates the operationof disengaging the detent |00 which is moved against the spring ||2 bythe force of the rotational movement of the stepping mechanism 20; itreadily disengages itself from the notches 82 by reason of the curvededges ||8 joining the U-shaped notches 82 with the periphery of thetable i8. The detent |00 does not enter intc the notches 82 very far dueto the retarding effect of the notch 88 in the plate 88, and, hence,there ls relatively little resistance given either by notches 82 or 88to the force exerted by the stepping mechanism 20 in rotating the tableI8 the distance between adjacent notches 82.

As has been previously set out, the stepping mechanism 20 actuates thetable I8 so that it will move the distance between adjacent notches 82,and the stepping mechanism also positions the nut blank so that it willbe engaged by the tapping tool without movement in any direction. Thismechanism is operated by the power cylinder |4 and is connected theretoby the piston rod |20 of the power cylinder. A yoke |22 which is adaptedto receive a cam block |24 s secured to the outer end of the piston rod.Bolted to the lower edge of the cam ,blcck |24 by bolts |28 is areciprocating member |28 which is formed by a pair of bars |80, |82secured together by bolts |84.

The upper bar |82 is formed with a recess |88 in its lower face whichprovides an opening for the reception of a pawl |88. The pawl ispivotally mounted on a bolt or stud |40 passed through the bars |82, andis biased against the ratchet wheel 88 by a pawl spring |42. The member|28 is prevented from sidewise movement by a guide |44 mounted in thelower part of the housing I8 on the upper surface of the bed l2. Thepawl |88 advances the ratchet wheel 88 one notch, which corresponds tothe spacing between adjacent notches 82 on table I8 on the retractilemovement of the piston rod |20 by the power cylinder I4. On the powerstroke of the cylinder the pawl |88 rides over the next tooth of theratchet wheel 88 and positions itself for another advancing movement ofthe stepping mechanism. There is a slight lost motion between the pawl|38 and the ratchet wheel 88 so that the finished nut can be released bythe clamping mechanism before the table I8 is rotated. Fig. 8illustrates the parts in the position they have immediately after thecam block' |24 has been disengaged from the clamping mechanism and justbefore the ratchet wheel 88 is rotated by the pawl |88 and the member|28.

As most clearly seen in Fig. 7, the nut blank A is held in position forthe tapping operation by a vertically reciprocable hollow plunger |46.The plunger |48 is almost as long as the height of the housing and isprovided at its upper end with a portion of reduced diameter |48 whichpasses through a bore |50 in the block 38, a hole |52 in the plate 84,and into the space which is formed by the facing edges of the recesses92 and the arcuate faces 88 of the plate 88. The cover plate 10 at thetapping position is provided with a hole I 54 which is counterbored at|56 on its upper surface and is tapered outwardly at |58 to form aconical seat on the lower surface of the plate 10 concentric with thehole |54. The chamfered edges of the nut A engage in the conical seat|58 when the plunger |48 is forced upwardly by the stepping mechanism.The top of the plunger |46 is machined so that its end surface isperpendicular to its central axis, and thus the nut blank is properlypositioned with its opening concentric with the bore |54, which in turnis concentric different set of table and with the tap, and with its flatbottom face perfectly square with the axis of the tap. The lower end ofthe plunger |48 is guided in a. bore |59 .which is drilled in the guideblock |44 so that there will be no wobbling movement of the plunger |46as it is reciprocated vertically. Intermediate its ends a pair ofcollars I 80 are positioned and are locked in place by set screws |82. Aspring |84 is secured between the upper collar |80 and the lower face ofthe block 38 so that the plunger I 48 will be constantly urged in adownward direction. The downward movement of the spring |84 is resistedby a pivotally mounted lever |88 which has brazed to its upper surface apair of fulcrum elements |88. As seen most clearly in Fig. 6, the lever|88 is pivoted on a shaft |10 which is mounted in the Walls 30, 32 ofthe housing. A pair of spacer sleeves |1I position the lever on theshaft |10 and the extent of its movement in a counter-clockwisedirection (Fig. 6) is resisted by an adjustable stop |12. The lever |88is provided with a bore |14 through which passes the plunger |46. At itsopposite extremity the lever 88 is forked to provide a recess |18 forthe reception of a roller |18 mounted on a shaft |80. The roller 18 isadapted to engage on the cam surface |82 of the cam block |24 when thepower cylinder I4 moves the cam block to the right (Fig. 6). When thishappens the lever |88 will pivot on the shaft |10 and will move theplunger I 46 upwardly against the force of the spring |84.

Before the device is operated it is essential that the plunger |48 bepositioned so that its upper surface is Hush with the surface 11 of theplate 84. This is done by sliding the plunger |46 relative to thecollars |60 and tightening the set screws |82. An opening |86 isprovided in the wall 30 so that a screw driver or Allen wrench may beinserted to adjust the set screws I 82. The table I8 and the plate 68with the arcuate edge 88 may be changed to accommodate nut blanks ofvarying sizes. The change is readily made by removing the bolts 54 and12 and substituting a plate. The differences between the different setslie in the thickness of the table and plate and the size of the recesses82.

As clearly seen in Fig. 7, the bore |50 is counterbored at |88 and theend of the counterbore is adapted to engage a shoulder |90 at the baseof the reduced diameter section |48 should the plunger |46 be movedupwardly by the clamping mechanism when an empty recess 92 is moved tothe tapping position during the operation of the device.

The operation of the indexing mechanism is as follows: After theoperation of the indexing mechanism has been synchronized to theoperation of the tapping tool, a supply of nut blanks are placed in thetray 22. The nut blanks are then placed by hand in the recesses 92 ofthetable I8 and the device is started to operate with the operation ofthe tapping tool. As the tap approaches the fixture the power cylinderI4 is adapted to commence a power stroke and to move the piston rod andits associated parts toward the left (Figs. 1, 2, 3 and 8), or towardthe right (Fig. 6). As the power stroke is continued the cam surface |82engages the roller |18 raising the lever |86 about -the pivot |10. Thismovement causes the fulcrum point |88 to be raised against the force ofthe spring |84 and because the spring |84 maintains the collars |80constantly against the fulcrum, the plunger |48 is raised in its guidebores |59, I 50. Assuming that a nut blank has been moved into positionabove the reciprocating plunger 46, its lower face will be engaged bythe upper face of the plunger |48, and its chamfered face will engage inthe conical seat |58, so that the bore of the nut bla-nk will beconcentric with the bore 'of the opening |54 and concentric with theaxis of .the tap. The powervwill continuously be applied -by thecylinder I4 all during the tapping operation, which means that the nutwill be held in the position shown in Fig. 7 during this time. As thetap forms the thread on the interior of the nuts, the chips of metalwill drop down through the interior of the plunger |48 and through theopening |84 in the bed plate I2 to a suitable receptacle.

After the tap has been removed at the completion of the tappingoperation, the valve 28 is actuated to reverse the action of thecylinder which commences a retractile stroke. On this movement of thecylinder the cam surface |82 will be drawn from engagement with therollers |18 and the spring |84 will force the plunger |48 to itsretracted position. This will drop the nut back onto the surface 11 ofthe plate 84. As soon as the nut has been returned to this position, thepawl |38, which has a slight lost motion, will engage a tooth in theratchet wheel 88 moving it one notch, thereby sweeping the completed nutaway from the tapping position and bringing up another nut blank to thetapping position. When this step has been completed the fixture isconditioned for another sequence of operations.

During the time the nut blank A was in its position over the plunger|48, the detent |00 engaged in the notches 98 and 98. During thestepping operation the detent was forced out of engagement with thenotches 98 and 98 and the edge of the detent rides on the periphery ofthe table I8. As the table I8 passes a notch 92 by the detent ittemporarily drops into this opening.

' scribes it as handling nut blanks, the mechanism 'is equally welladapted for feeding and positioning other blanks of non-circular outlineor provided with a pair of opposite flat faces adapted to fit betweenthe sides of the notches 92 in the table it; and the mechanism isadapted for holding such parts not only for tapping but for drilling,reaming, milling and various other operations in which the employment ofthis mechanism will prove a factor contributing notably to high speedproduction.

While we have described and disclosed only one embodiment of ourinvention, it will be apparent to those skilled in the art that numerousminor changes and modifications may be made therein without departingfrom the spirit and scope of our invention, and, therefore, we desire tobe limited only by the appended claims.

What we claim as new and useful and desire to secure by United StatesLetters Patent is:

1. An indexing mechanism of the class described, comprising a rotatabletable having blank receiving notches in its periphery each dimensionedto receive a blank in a definite position relative to said table, meansfor rotating said table the distance between centers of adjacent blankreceiving notches, guide means for retaining each of said blanks in areceiving notch in said definite position relative to said table, andclamping means engaging a blank independent- 1y of the table and holdingsaid blank in position during a work operation.

" 2. An indexing mechanism of the class described, a rotatablev tablehaving blank receiving notches in its periphery each dimensioned toreceive a blank in a definite position relative to said table and meansfor rotating said table the distance between centers of adjacent blankreceiving notches, a blank in one of said notches being thereby centeredrelative to a tool of the machine, guide means retaining each of theblanks in a blank receiving notch in the said definite position duringrotation of said table, and clamping means engaging a blankindependently of the table and cooperating with said notch for holdingthe blank in position during a work operation.

3. An indexing mechanism of the class described, comprising a powercylinder, a rotatable table having blank receiving notches in itsperiphery, means operatively connected to said power cylinder forrotating said table the distance between centers of adjacent blankreceiving notches for each stroke of said power cylinder in onedirection, guide means positioning each of the blanks in a receivingnotch in correct position relative to the tool of the machine, andclamping means engaging a blank independently of the table for holdingthe blank in position during Va work operation, said clamping meansbeing operatively connected to said power cylinder and adapted to beactuated to clamping position by said power cylinder on a stroke in theother direction.

4. Anv indexing mechanism of the class decribed for the step-by-stepadvancements of a blank to a position in which it may have a workoperation performed thereon, including in combination a rotatable tablehaving blank receiving notches in the periphery thereof, a steppingmechanism adapted to advance said table the distance between centers ofadjacent notches. clamping means at the work position adapted to engagea blank independentlyof the table and to hold it during a workoperation, and a power cylinder operatively connected to said steppingmechanism and to said clamping means whereby said stepping mechanismwill be actuated by said power cylinder on a stroke in one direction`and said clamping means will be moved to clamping position by said powercylinder on a stroke in the opposite direction.

5. An indexing mechanism of the class described, comprising incombination a housing, a bearing block mounted on one side of saidhousing. a shaft mounted for rotation in said bearing block, a tablehaving blank receiving notches formed at regular intervals in itsperiphery secured to said shaft, a slot formed in said housing toreceive a portion of said table so that at least one blank receivingnotch'is enclosed therein, an opening in said housing adapted to receivea tool. said opening coinciding with a notch of said table when thenotch is enclosed in said slot, means for clamping the nut blank againsta wall of said slot when its bore is axially aligned with said opening.and means for intermittently turning said shaft through the interval atwhich said notches are spaced and means alternately actuating saidclamping means. l 6. An indexing mechanism of the class described.comprising in combination a housing, a bearing block mounted on one sideof said housing, a shaft mounted for rotation in said bearing block, atable having nut receiving notches formed in its periphery secured tosaid shaft, a sloi'l formed in said housing to receive a portion 0f saidtable so that at least one nut receiving notch is enclosed therein. aplate located beneath said table cooperating with the lower wall of saidslot to form a track on which the nut blanks may be slid bv rotation ofsaid table. an opening in said track within said slot, reciprocableclamping means movable through said opening, a break in said track toallow the tapped nut to drop free of said table. and means forintermittently and alternately actuating said shaft and said clampingmeans.

'7. In an indexing mechanism the combination of a rotatable circulartable having nut blank receiving notches in its periphery. a verticallydisposed shaft to which said table is secured, bearing block meansmountingf said shaft for rotation. means for advancing` said table thedistance between notches comprising a ratchet wheel iixedly mounted onsaid shaft. a reciprocable bar having a pawl therein adapted to engagethe tooth of said ratchet wheel to rotate said shaft when said bar ismoved in one direction. means for reciprocating said bar, andrestraining means for preventing rotational movement of said table whensaid bar is moved in the opposite direction comprising, a second set ofnotches in the periphery of said table alternating with said notches ofthe first set. a detent mounted on said bearing block. means adapted toengage in a notch of said second set when the nut blank is in tappingposition. and resilient means constantly urging said detent toward notchengaging position.

8. The combination set forth in claim '1, together with means by whichsaid detent is prevented from fully entering into a notch of said firstset, said detent having an inclined face engageable with the outercorner of a notch of said rst set so that it is displaced from saidnotch when said table is rotated.

9. In an indexing mechanism of the class described, the combination of arotatable circular table having nut blank receiving notches formed inits periphery. a housing having a slot formed therein to receive aportion of said table, said slot having an arcuate wall extendingadjacent the periphery of the table an opening formed in said housingand communicating with said slot, nut blank clamping means reciprocablethrough said opening, means for advancing said table the distancebetween adjacent notches, said advancing means being so adjusted that itwill bring successive notches to coincide with said opening at the endof each of its movements, a bore in said housing opposite said openingand through which a tap is adapted to pass during a tapping operation,and means for actuating said clampsaid plunger being open at its lowerend and normally having its upper face ush with the lower wall of saidslot, and means to actuate said plunger toward said conical seat whensaid table has positioned a nut in said slot coincident with y saidopening and said wall, so that a nut will ing means so that it willclamp the nut blank between its outer end and a wall of said slot.

10. In an indexing mechanism of the class described, the combination ofa rotatable table having nut receiving notches in its periphery, meansfor advancing said table the distance between adjacent notches, ahousing having a slot formed therein to receive an edge of said table sothat at least one nut receiving notch is completely enclosed therein, anopening formed in a wall of said housing connecting the interior thereofwith said slot, a hollow plunger reciprocable through said opening, anopening in the opposite wall of said housing smaller than a nut blank toadmit a tool to operate on the blank, and means to actuate said plungertoward said opposite wall to nut clamping position when said table haspositioned a nut blank in said slot coincident with the latter opening.y

11. In an indexing mechanism of the class described, the combination ofa rotatable table having nut receiving notches in its periphery, meansto advance said table the distance between adjacent notches, a housinghaving an arcuately shaped slot formed in the top wall thereof toreceive an edge of said table so that at least one nut receiving notchis completely enclosed therein, a bore in said top wall connecting theinterior of said housing with said slot and through which a tap isadapted to. pass, a conical seat coaxial with said bore on the interiorof said slot, a hollow plunger reciprocable in said opening,

be clamped between the top face of said plunger and said conical seat tohold it in alignment with a tap.

12. An indexing mechanism of the class described, comprising a rotatablecircular table having nut blank receiving notches in its periphery, thewidth of each notch being substantially the same asthe width of a nutblank. measured between opposite lateral faces thereof and the depth ofeach notch being substantially equal to the diameter of a nut blankmeasured between opposite corners thereof, arcuate guard means extendingclosely adjacent the periphery of the table to hold the blanks in placein said notches, and clamping means to engage the upper and lower facesof a nut blank to hold it in position during a tapping operation.

13. In an indexing mechanism as defined in claim l2, means operableintermittently to rotate said table and adapted to advance the table thedistance between centers of adjacent notches at each actuation, andmeans for actuating said clamping means intermittently in alternationwith said table rotating means.

14. In an indexing mechanism as defined in claim 12, means operableintermittently to rotate said table and adapted to advance the table thedistance between centers of adjacent notches at each actuation, andrestraining means for preventing rotational movement of said tableexcept when so advanced, comprising a second set of notches in theperiphery of said table alternating with said notches of the rst set butof substantially less depth, a beveled detent positioned to engage in anotch of said second set when the nut blank is in tapping position,resilient means constantly urging said detent toward notch-engagingposition, andmeans limiting movement of the detent in response to saidresilient means at a position in which its beveled face will engage acorner of each nut receiving Vnotch to be cammed outwardly thereby whenthe table is rotated.

HOMER VERHN HOFFMAN. VON RENOLD KAUFMAN.

